Sorry buddy, that is okay though.
I can stop being part of the Kingdom of God by simply no longer praying to God, no longer giving him thanks, no longer reading the scriptures, and live totally and completely in my flesh if I desire so.
God gave us the ability to choose and that is the part I believe you are missing brother. You choose to have faith and trust God, or you do not.
Like the scripture said before:
Hebrews 3:12 Be careful then, dear brothers and sisters. Make sure that your own hearts are not evil and unbelieving, turning you away from the living God.
And I believe the only reason one may defend "Once saved always saved" is because that is the easier road to choose rather than the hard work of the narrow road of faith, which causes a person to be of faith, humble, patience, kind, forgiving towards others who have done them wrong, admitting ones faults to God in thankfulness of what He has done for all human beings in the world because of the Son of God, Jesus Christ. Praying and growing from a child of God into a Son of Daughter of God.
So if there is no choice to choose faith, then everyone is just elected and that leaves no room to choose at all, and that is all "Bullsh%%", it is sad to hear people say that "ONLY THOSE WHO ARE ELECTED ARE Chosen".
When in reality God is calling all people to come to his son, and they have to make a the choice of believe or not to believe.
Anyway you can choose and decide how you are going to believe as it doesn't effect me on my stances already presented to you which may cause you to be troubled by what is being said.
God bless... Nothing has really changed since the days of Jesus walking around. All of still make choices, whether we forgive others for what they done to us, and place faith in Jesus.